1. Field of the Invention
This invention relates to insulation and construction materials. In one of its aspects it relates to material used for thermal and acoustic insulation. In another of its aspects it relates to vacuum insulation materials i.e. insulating materials containing enclosed spaces in which the pressure is less than atmospheric pressure. In another of its aspects this invention relates to construction materials containing enclosed spaces in which the pressure is less than atmospheric pressure. In yet another of its aspects this invention relates to ultralight construction materials. In still another of its aspects this invention relates to the production of vacuum insulation materials. In still another of its aspects this invention relates to the production of construction materials containing enclosed spaces in which the pressure is less than atmospheric pressure. In yet another aspect this invention relates both (1) to providing hollow fibers having enclosed spaces in which the pressure is less than atmospheric pressure and (2) to combining these fibers into mat or cloth, as by entangling the fibers or weaving the fibers.
2. Description of the Prior Art
Vacuum insulation techniques have been known for use in various applications for both thermal and acoustic insulation material. Such material makes use of the advantage of having a reduced number of molecules in a vacuum chamber encapsulated within the material so that the transfer of heat or sound is reduced as compared to material having chambers encapsulating gases at atmospheric pressure or higher pressures. Obviously, the greater the reduction of pressure within a vacuum chamber the more effective will be the barrier to the transfer of heat or sound energy through the chamber and increasing the ratio of open space to supporting structure also reduces the transfer of heat or sound through an insulating material.
While several approaches have been tried in the production of vacuum insulation the most common schemes have relied on producing air-tight enclosing structures that are supported from within by loosely packed filler which upon the evacuation of gas from the structure prevents the structure from collapsing on itself, but still provides interstices between the units of filler from which gas can be withdrawn. After the evacuation of gas, the structure is sealed to maintain the vacuum.
Other production approaches enclose within a single air-tight, outer structure a multiplicity of either elongated, relatively flat, air-tight, bag structures or elongated, sausage-shaped, air-tight structures of relatively small diameter, either of which are supported on the inside by microporous insulation material. Gas is withdrawn from the individual, filled structures and each is individually sealed before the multiplicity of structures is enclosed within an air-tight outer structure and the outer structure is sealed.
Although vacuum insulation produced by the processes discussed above is effective, the evacuation and sealing of the filler supported structures can be tedious and costly. The present invention eliminates the need to evacuate gases from filler supported structures and provides material that can retain its vacuum characteristic after being cut or machined.
Also known in the prior art is the method set out in U.S. Pat. No. 4,024,309, in which a foamed glass panel is formed under vacuum conditions and passed through a metal cladding operation before being discharged into atmospheric conditions. A foamed glass having contained chambers of less than atmospheric pressure is thereby produced with the metal cladding providing structural strength to aid in protecting the air-tight seals of the more fragile foamed glass structures. The metal cladding is applied for structural strength and, since the cladding is not described as encapsulating the foam and is pierced after its application, is not incorporated to provide an air-tight seal around the foamed glass.
The technique, described herein, that is used for producing vacuum insulation can be used, by the process of this invention, to produce construction materials i.e. materials, that because of the innate strength of the materials used, can be formed into shapes containing bubbles in which the contained gas is at a pressure less than atmospheric. Such construction materials are useful in constructing products in which the combination of lightness and strength of material is an asset. Among such products are automobiles, airplanes, spacecraft and boats.
Techniques described herein can also be used to produce insulating layers for fabric useful in clothing, bed covers, and camping gear. With the proper choice of construction material the performance and look of down filled fabric can be duplicated without the drawback of potential, feather allergy.
It is also easily understood that bubbles having an internal pressure of less than atmospheric pressure can be incorporated into construction material at sufficiently high ratio to the total amount of solid material in the structure and encapsulating material that the resulting product would be buoyant in a fluid, liquid or gas, of greater density.
Note that for the purposes of this invention the term "bubble" includes any space surrounded by an enclosing material. It is used herein synonymously with void, chamber, pocket, interstice, area of space and other such terms. Also note that the terminology hereinafter describing the material of the invention as having at least one enclosed chamber therein refers to material that typically has numerous chambers or is filled with a multitude of chambers.
It is, therefore, an object of the present invention to provide an improved process for the manufacture of vacuum insulating materials.
It is another object of this invention to provide vacuum insulating materials made by the process of this invention.
It is still another object of this invention to provide a process for the manufacture of vacuum insulating materials eliminating the need to evacuate gases from the insulating material structure.
It is still another object of this invention to provide vacuum insulating materials of improved structure.
It is another object of this invention to provide construction materials and a method for producing construction materials having encapsulated therein bubbles or pockets within which the pressure is less than atmospheric pressure.
It is yet another object of this invention to provide a fibrous, insulating material that can be incorporated into fabric.
These and other objects and advantages of the present invention will become evident to those skilled in the art by reference to the following description and drawings and the appended claims.